KR20230168687A - Porous electrodes for lithium ion capacitors, lithium ion capacitors including the same, and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a porous electrode for a lithium ion capacitor, a lithium ion capacitor including the same, and a manufacturing method thereof, and is intended to improve the coating process of the electrode. The present invention includes a current collector having a first side and a second side opposite to the first side, a first electrode layer formed on the first side, and a second electrode layer formed on the second side, and the first and second electrode layers Provided is a porous electrode for a lithium ion capacitor having at least one of the following and a plurality of holes integrally penetrating a current collector.

Description

Porous electrodes for lithium ion capacitors, lithium ion capacitors including the same, and method for manufacturing the same {Porous electrodes for lithium ion capacitors, lithium ion capacitors including the same, and method for manufacturing the same}

The present invention relates to a super capacitor, and more specifically, to a porous electrode for a lithium-ion capacitor, a lithium-ion capacitor including the same, and a method of manufacturing the same.

A super capacitor is called a high-performance electric storage device or large-capacity storage battery, and is a device that can supplement or replace the battery of an electric vehicle. It has the advantage of being able to produce instantaneous high output compared to regular secondary batteries. Because of these characteristics, it is installed in electric vehicles, etc. as a device to supplement the performance of secondary batteries. Super capacitors can be used when instantaneous high output is required, such as starting or rapid acceleration.

Types of these super capacitors include electric double layer capacitors (EDLC) that use activated carbon as electrodes, pseudo capacitors (pseudo capacitors) that use transition metal oxides and conductive polymers as electrode materials, and lithium-ion capacitors (LIC). ; There are hybrid capacitors such as Lithium Ion Capacitor.

Lithium-ion capacitors are a new concept of power storage device that combines the high output and long life characteristics of existing electric double-layer capacitors with the high energy density of lithium-ion batteries. In general, capacitor electrodes are manufactured by applying an electrode slurry containing an electrode active material, a binder, and a conductive material to a current collector. At this time, when a through hole is formed in the current collector and the electrode slurry is applied to the through hole, lithium ions can move through the through hole, so the utilization rate of the active material can be increased.

Accordingly, a method of manufacturing a porous current collector in batches through an etching process for the current collector was proposed. However, when applying electrode slurry to a current collector with a through hole, the electrode slurry may pass through the through hole and leak to the back side of the current collector, contaminating the back side. In addition, there is a problem that the surface of the electrode layer becomes non-uniform, resulting in poor electrode coating workability.

Public Patent Publication No. 10-2009-0103838 (published on October 1, 2009) Public Patent Publication No. 10-2013-0026789 (published on March 14, 2013)

Therefore, the purpose of the present invention is to provide a porous electrode for a lithium-ion capacitor that can improve the coating process of the electrode, a lithium-ion capacitor including the same, and a method for manufacturing the same.

In order to achieve the above object, the present invention includes a current collector having a first side and a second side opposite to the first side; a first electrode layer formed on the first surface; and a second electrode layer formed on the second surface; a porous electrode for a lithium ion capacitor including at least one of the first and second electrode layers and a plurality of holes integrally penetrating the current collector. to provide.

The current collector is a metal thin film.

The first and second electrode layers include a negative electrode active material.

The plurality of holes integrally penetrate one of the first and second electrode layers and the current collector.

The plurality of holes may include a plurality of first holes integrally penetrating the current collector and the first electrode layer; and a plurality of second holes integrally penetrating the current collector and the second electrode layer, wherein the first holes and the second holes are formed to alternate with each other.

Each of the plurality of holes has a diameter shorter than the depth.

The total area of the plurality of holes is 5% or less based on the area of the first or second side of the current collector.

The present invention includes a current collector having a first side and a second side opposite to the first side, a first electrode layer formed on the first side, and a second electrode layer formed on the second side, and at least one of the second electrode layers and an electrode having a plurality of holes integrally penetrating the current collector.

The present invention also includes preparing a current collector having a first side and a second side opposite the first side; forming a first electrode layer on the first surface; forming a second electrode layer on the second surface; and forming a plurality of holes integrally penetrating at least one of the first and second electrode layers and the current collector.

In the step of forming the plurality of holes, the plurality of holes may be formed using a laser.

The present invention forms a hole after forming an electrode layer on a current collector, so that when electrode slurry is applied to a current collector with an existing through hole, the electrode slurry passes through the through hole and leaks to the back side of the current collector. It is possible to provide an electrode coating process that improves the problem of contamination of the back side.

In addition, the present invention may cause some capacity loss by forming holes in the current collector and electrode layer, but the capacity loss can be offset by increasing the utilization rate of the active material forming the electrode layer by facilitating the movement of lithium ions through the holes. there is.

1 is a flowchart showing a method of manufacturing a porous electrode for a lithium ion capacitor according to a first embodiment of the present invention.
Figures 2 to 5 are diagrams showing each step according to the manufacturing method of Figure 1.
Figure 6 is a flowchart showing a method of manufacturing a porous electrode for a lithium ion capacitor according to a second embodiment of the present invention.
FIG. 7 is a diagram showing the steps of forming a second hole according to the manufacturing method of FIG. 6.

It should be noted that in the following description, only the parts necessary to understand the embodiments of the present invention will be described, and descriptions of other parts will be omitted without departing from the gist of the present invention.

The terms or words used in the specification and claims described below should not be construed as limited to their usual or dictionary meanings, and the inventor should use the concept of terminology appropriately to explain his/her invention in the best way. It must be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined clearly. Therefore, the embodiments described in this specification and the configurations shown in the drawings are only preferred embodiments of the present invention, and do not represent the entire technical idea of the present invention, and therefore, various equivalents can be substituted for them at the time of filing the present application. It should be understood that there may be variations.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the attached drawings.

[First Example]

Figure 5 is a cross-sectional view showing a porous electrode for a lithium ion capacitor according to the first embodiment of the present invention.

Referring to FIG. 5 , the porous electrode 60 according to the first embodiment includes a current collector 10, a first electrode layer 20, and a second electrode layer 30. The current collector 10 has a first side and a second side that is opposite to the first side. The first electrode layer 20 is formed on the first side of the current collector 10. The second electrode layer 30 is formed on the second side of the current collector 10. And a plurality of first holes 40 are formed that integrally penetrate the current collector 10 and the first electrode layer 20.

Here, the current collector 10 is a metal thin film. The material for the metal thin film is not particularly limited as long as it has high conductivity without causing electrochemical changes in the lithium ion capacitor. For example, aluminum, copper, stainless steel, nickel, titanium, and alloys thereof may be used as materials for the metal thin film.

The first electrode layer 20 and the second electrode layer 30 include a negative electrode active material. Here, the negative electrode active material can be a material that can reversibly support lithium ions. For example, the negative electrode active material may be a crystalline carbon material such as graphite or non-graphitizable carbon, a carbon material such as hard carbon or coke, or a polyacene-based material (PAS).

The plurality of first holes 40 each have a diameter shorter than the depth. If the diameter of the first hole 40 is too large, it is not desirable because the strength of the porous electrode 60 may be weakened. And the plurality of first holes 40 are uniformly distributed on the porous electrode 60.

Additionally, the total area of the plurality of first holes 40 is 5% or less based on the area of the first or second surface of the current collector 10. Since some capacity loss may occur by forming the first hole 40 in the current collector 10 and the first electrode layer 20, it is preferable to form the first hole 40 to 5% or less to minimize this. . The capacity loss that occurs can be offset by smoothing the movement of lithium ions through the first hole 40 and increasing the utilization rate of the active material forming the first electrode layer 20.

The manufacturing method of the porous electrode 60 according to the first embodiment will be described in detail with reference to FIGS. 1 to 5 as follows. Here, Figure 1 is a flowchart showing a method of manufacturing a porous electrode for a lithium ion capacitor according to a first embodiment of the present invention.

Referring to FIG. 1, the method for manufacturing a porous electrode according to the first embodiment includes preparing a current collector (S10), forming a first electrode layer on the first side of the current collector (S20), and forming a first electrode layer on the first side of the current collector (S20). It includes forming a second electrode layer on two sides (S30) and forming a hole in the current collector and the first electrode layer (S40).

Figures 2 to 5 are diagrams showing each step according to the manufacturing method of Figure 1.

First, as shown in FIG. 2, the current collector 10 is prepared in step S10.

The current collector 10 uses a metal thin film in which no holes are formed. Since no holes are formed in the current collector 10, in the subsequent step of forming the first and second electrode layers, the electrode slurry of the first electrode layer to be formed on the first surface of the current collector 10 The problem of contaminating the second electrode layer to be formed on the second surface of the current collector 10 can be fundamentally solved. Conversely, the problem of the electrode slurry of the second electrode layer to be formed on the second side of the current collector 10 contaminating the first electrode layer to be formed on the first side of the current collector 10 can be fundamentally solved.

Next, as shown in FIG. 3, the first electrode layer 20 is formed on the first side of the current collector 10 in step S20.

The first electrode layer 20 can be formed by preparing an electrode slurry containing an electrode active material, a binder, and a conductive material, applying it to the first side of the current collector 10, compressing it, and then drying it. As described above, since there are no holes in the current collector 10 on which the first electrode layer 20 is formed, the electrode slurry forming the first electrode layer 20 is deposited on the first side of the current collector 10. 10) It does not move to the second side.

Here, the electrode active material constituting the electrode slurry is a negative electrode active material. Specifically, the negative electrode active material may be crystalline carbon materials such as graphite and non-graphitized carbon, carbon materials such as hard carbon and coke, and polyacene-based materials (PAS).

The conductive material is made of an allotrope of carbon in the form of particles that have conductivity and do not have pores capable of forming an electric double layer. Specifically, the conductive material includes conductive carbon black such as furnace black, acetylene black, and Ketjen black.

The binder is a compound that can bind the electrode active material and the conductive material to each other, and various materials that have the property of dispersing in a solvent can be used. Specifically, the binder may include high molecular compounds such as fluoropolymer, diene polymer, acrylate polymer, polyimide, polyamide, and polyurethane polymer.

Next, as shown in FIG. 4, the second electrode layer 30 is formed on the second side of the current collector 10 in step S30.

As described above, since there are no holes in the current collector 10 on which the second electrode layer 30 is formed, the electrode slurry forming the second electrode layer 30 is deposited on the second side of the current collector 10. It does not move to the first side of 10).

The negative electrode active material used in the second electrode layer 30 is the same as the negative electrode active material used in the first electrode layer 20, and the forming step of the second electrode layer 30 is the same as step S20 of forming the first electrode layer 20. Therefore, the description thereof is omitted.

Finally, as shown in FIG. 5, in step S40, a plurality of first holes 40 are formed to integrally penetrate the current collector 10 and the first electrode layer 20, thereby forming the porous electrode according to the first embodiment. (60) can be manufactured.

Here, the first hole 40 can be formed using a laser.

The first hole 40 is preferably a hole that penetrates the current collector 10 and the first electrode layer 20 as one piece, but a groove may be formed in a portion of the second electrode layer 30 during the process of forming the hole. there is.

Meanwhile, in the first embodiment, an example of forming the first hole 40 in the first electrode layer 20 and the current collector 10 is disclosed, but the present invention is not limited to this. For example, a hole (hereinafter referred to as a ‘second hole’) may be formed in the second electrode layer and the current collector. Alternatively, a first hole may be formed in the first electrode layer and the current collector, and a second hole may be formed in the second electrode layer and the current collector.

[Second Embodiment]

Figure 7 is a cross-sectional view showing a porous electrode for a lithium ion capacitor according to a second embodiment of the present invention.

Referring to FIG. 7 , the porous electrode 70 according to the second embodiment includes a current collector 10, a first electrode layer 20, and a second electrode layer 30. The current collector 10 has a first side and a second side that is opposite to the first side. The first electrode layer 20 is formed on the first side of the current collector 10. The second electrode layer 30 is formed on the second side of the current collector 10. And a plurality of first holes 40 integrally penetrating the current collector 10 and the first electrode layer 20 and a plurality of second holes integrally penetrating the current collector 10 and the second electrode layer 30 ( 50) is formed.

The first holes 40 and the second holes 50 may be formed to be staggered so that the first holes 40 and the second holes 50 can be uniformly distributed throughout the porous electrode 70 .

Since the porous electrode 70 according to the second embodiment has the same structure as the porous electrode according to the first embodiment, except that the second hole 50 is additionally formed in the second electrode layer 30, the first embodiment The description of the parts overlapping with the porous electrode according to the example will be omitted, and the description will be focused on the first hole 40 and the second hole 50 as follows.

The plurality of first holes 40 and second holes 50 each have a diameter shorter than the depth. And the plurality of first holes 40 and second holes 50 are uniformly distributed on the porous electrode 70.

Additionally, the total area of the first hole 40 and the second hole 50 is 5% or less based on the area of the first or second side of the current collector 10.

The manufacturing method of the porous electrode 70 according to the second embodiment will be described in detail with reference to FIGS. 6 and 7 as follows. Here, Figure 6 is a flowchart showing a method of manufacturing a porous electrode for a lithium ion capacitor according to a second embodiment of the present invention.

Referring to FIG. 6, since steps S10 to S40 of the manufacturing method of the porous electrode 70 according to the second embodiment proceed in the same manner as the manufacturing method of the porous electrode 60 according to the first embodiment, The explanation is omitted.

Thereafter, as shown in FIG. 7, a plurality of second holes 50 are formed in the current collector 10 and the second electrode layer 30 in step S50, thereby forming the porous electrode 70 according to the second embodiment. It can be manufactured.

Here, the second holes 50 are formed to be staggered with the first holes 40 so that they can be uniformly distributed over the entire surface of the porous electrode 70 together with the first holes 40 .

Like the first hole 40, the second hole 50 can be formed using a laser.

The second hole 50 is preferably a hole that penetrates the current collector 10 and the second electrode layer 30 as one piece, but a groove may be formed in a portion of the first electrode layer 20 during the process of forming the hole. there is.

As described above, the manufacturing method according to an embodiment of the present invention forms a hole using a laser after forming an electrode layer on the current collector, so when applying the electrode slurry to the current collector with an existing through hole formed, the electrode slurry penetrates. It is possible to provide an electrode coating process that improves the problem of contamination of the back side of the current collector by leaking through the hole.

Additionally, a lithium ion capacitor according to an embodiment of the present invention may include a porous electrode according to an embodiment of the present invention as a cathode, and may include a positive electrode, a separator, and an electrolyte. Except for the porous electrode according to the present invention, the anode, separator, and electrolyte materials used in general lithium ion capacitors can be used.

[Experimental examples and comparative examples]

In order to confirm the characteristics of the porous electrode for a lithium ion capacitor according to the first embodiment of the present invention, electrodes according to experimental examples and comparative examples were manufactured.

The first comparative example is a porous electrode in which the total area of holes penetrating the current collector is 30% to 40% of the area of the first surface of the current collector. The porous electrode according to the first comparative example is an electrode equipped with a general porous current collector, and no holes are formed in the double-sided electrode layers (first and second electrode layers).

The second comparative example is a porous electrode in which the total area of holes penetrating the current collector and the double-sided electrode layer is 1% or less based on the area of the first side of the current collector, and the third comparative example is a porous electrode that is more than 1% and less than 5%. It is an electrode.

The first experimental example is a porous electrode in which the total area of holes penetrating the current collector and the single-sided electrode layer (first electrode layer) is 1% or less based on the area of the first side of the current collector, and the second experimental example is 1%. It is a porous electrode with an excess of 5% or less.

The characteristics of the experimental examples and comparative examples are described in detail with reference to Table 1 and Table 2 as follows.

Table 1 below shows that the lithium ion capacitor including the porous electrode of the first, second, and third comparative examples and the first and second experimental examples was charged and discharged at 1C-rate at 0.04A and then at 100C-rate at 4A. It represents the discharge capacity measured by charging and discharging and the capacity maintenance ratio, which is the ratio of the discharge capacity during 100C-rate charging and discharging to the discharge capacity during 1C-rate charging and discharging.

division When charging and discharging at 1C,
Discharge capacity (mAh) When charging and discharging at 100C,
Discharge capacity (mAh) Capacity maintenance rate (%) First comparative example 40.9 28.8 70 Second comparative example 39.7 32.7 82 Third comparative example 39.4 32.2 82 First Experimental Example 41.8 34.6 83 Second experimental example 41.2 33.8 83

Referring to Table 1, it can be seen that when using the porous electrodes of the first and second experimental examples, the discharge capacity and capacity retention rate are higher than when using the porous electrodes of the first, second, and third comparative examples.

Table 2 below measures the equivalent series resistance (DC-ESR) of the lithium ion capacitor including the porous electrode of the first, second, and third comparative examples and the first and second experimental examples, and shows the DC-ESR compared to the first comparative example. It represents ESR.

division DC-ESR (mohm) DC-ESR compared to Comparative Example 1 (%) First comparative example 94.51 100 Second comparative example 87.9 92 Third comparative example 87.9 93 First Experimental Example 88.14 93 Second experimental example 89.01 94

Referring to Table 2, it can be seen that when using the porous electrodes of the first and second experimental examples, the DC-ESR is lower than when using the porous electrode of the first comparative example.

Meanwhile, the embodiments disclosed in the specification and drawings are merely provided as specific examples to aid understanding, and are not intended to limit the scope of the present invention. It is obvious to those skilled in the art that in addition to the embodiments disclosed herein, other modifications based on the technical idea of the present invention can be implemented.

10: Current collector
20: first electrode layer
30: second electrode layer
40: 1st hole
50: 2nd hole
60, 70: porous electrode

Claims (10)

a current collector having a first side and a second side opposite the first side;
a first electrode layer formed on the first surface; and
It includes a second electrode layer formed on the second surface,
A porous electrode for a lithium ion capacitor having a plurality of holes integrally penetrating at least one of the first and second electrode layers and the current collector. According to paragraph 1,
A porous electrode for a lithium ion capacitor, wherein the current collector is a metal thin film. According to paragraph 1,
A porous electrode for a lithium ion capacitor, wherein the first and second electrode layers include a negative electrode active material. According to paragraph 1,
A porous electrode for a lithium ion capacitor, wherein the plurality of holes integrally penetrate one of the first and second electrode layers and the current collector. According to paragraph 1,
The plurality of halls are
a plurality of first holes integrally penetrating the current collector and the first electrode layer; and
It includes a plurality of second holes integrally penetrating the current collector and the second electrode layer.
A porous electrode for a lithium ion capacitor, wherein the first hole and the second hole are formed alternately with each other. According to paragraph 1,
A porous electrode for a lithium ion capacitor, wherein each of the plurality of holes has a diameter shorter than the depth. According to paragraph 1,
A porous electrode for a lithium ion capacitor, wherein the total area of the plurality of holes is 5% or less based on the area of the first or second surface of the current collector. A current collector having a first side and a second side opposite to the first side, a first electrode layer formed on the first side, and a second electrode layer formed on the second side, wherein the first and second an electrode formed with a plurality of holes integrally penetrating at least one of the electrode layers and the current collector;
A lithium-ion capacitor containing a. Preparing a current collector having a first side and a second side opposite the first side;
forming a first electrode layer on the first surface;
forming a second electrode layer on the second surface; and
forming a plurality of holes integrally penetrating at least one of the first and second electrode layers and the current collector;
A method of manufacturing a porous electrode for a lithium ion capacitor comprising a. According to clause 9,
A method of manufacturing a porous electrode for a lithium ion capacitor, characterized in that, in the step of forming the plurality of holes, the plurality of holes are formed using a laser.

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